A Ranger is dropped off in the woods at 8 am for an advanced land navigation test. His instructions are to head due north for 20 kilometers to reach a small town. The test ends when he reaches the local Bar where the people adminstrating the test will be waiting. The Ranger is wearing comfortable clothes/hiking boots and carries his wallet, a watch, a canteen full of water, and a compass. Even going at a leisurely pace, the course is usually completed in under 4 or 5 hours. The Ranger never made it to the town; he was found and picked up near dusk and taken home. What went wrong?

Is he human? Was he the victim of a prank? Was he dropped off at the correct location? Is the town actually there? Is the bar actually there? Does something interfere with the operation of the compass? something he is carrying? something he encounters while travelling? Does he in fact travel due north? Does he travel on foot? Does he travel at a leisurely pace? faster? slower? not at all? Is dusk less than 4-5 hours after 8 am? Was he still alive when he was picked up? Was he in good health? Was he in a different bar? in a different town?

Is he human? YesWas he the victim of a prank? NoWas he dropped off at the correct location? YesIs the town actually there? YesIs the bar actually there? YesDoes something interfere with the operation of the compass? No something he is carrying? No something he encounters while travelling? NoDoes he in fact travel due north? YesDoes he travel on foot? YesDoes he travel at a leisurely pace? Probably faster? Possibly slower? Maybe not at all? not likely (irr -> Maybe a short bathroom break)Is dusk less than 4-5 hours after 8 am? NoWas he still alive when he was picked up? YesWas he in good health? YesWas he in a different bar? No in a different town? No

Are there any extra contraints that you haven't told us about (e.g. he has to carry a couple of elephants on his shoulders)? No, he only had with him what I mentioned. Anything I didn't mention, he doesn't have it. (Nobody get smart alec on me now and start asking about missing legs or underwear, please. His body, hair, and garments were all intact.)

Okay. He didn't reach his final destination because - he got lost - there was ambiguity with regards to direction - he was tired - he was physically incapable of completing the task - he was mentally incapable of completing the task - natural intervention (e.g. snow/rain) - something else?

Okay. He didn't reach his final destination because - he got lost Yope- there was ambiguity with regards to direction Yes- he was tired No- he was physically incapable of completing the task No- he was mentally incapable of completing the task Noish- natural intervention (e.g. snow/rain) No- something else? Noish

Did go towards magnetic north whereas the town was geographical north? Correct! I figured this wouldn't last long with this group. Which means it's time for the...

*******************SPOILER***********************

The Ranger is an Army Ranger that has been training at Fort Benning, GA. Down south, the Grid-Magnetic angle is so small that even on large courses like this one, it's negligible (you wind up only a few hundred meters off on long courses) so nobody ever takes it into consideration. However, when soldiers from the south move north to places like Fort Lewis, WA, where the GM angle is 21-22 degrees, they still forget to add it to their azimuth and thus wind up far off course. On a 20 km course like this, that means the Ranger was over 7 km away from the town when he got to the end of his pace count. He knew exactly where he was with respect to his start point, but that wouldn't help him find the town. Forgetting about the GM angle is a surprisingly common problem in Military Land Navigation training.

Oops - didnt notice the woods and towns, sorry. Might be a while before that happens in Antarctica. And you missed John's questions. I've been cross-posting too much around his posts Is the confusion related to the direction North? Is it related to 20km?

The polarization of the earth DOES switch every so often. And every so often usually means once every few million years. This puzzle revolved mainly around that fact that magnetic north isn't where the north arrow on our maps says it is. Maps are flat and don't account for the contour of the earth, hence the location of 'north' is rather ambiguous.

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